Method and apparatus for malting

ABSTRACT

A method and apparatus for carrying out a malting process comprising means for efficiently turning over the grain mass in a bottom to top fashion by directing grain from adjacent to the bottom of the vessel to the centre of the bottom of the vessel from where it is elevated above the grain mass and redistributed back on top of the grain mass. The apparatus can be used for any stage of the malting process.

FIELD OF THE INVENTION

The present invention relates to the malting of grain, particularlybarley, including all five phases of the malting process, namely drying,steeping, germinating, kilning, and roasting, and provided meansintended for use in that process.

BACKGROUND TO THE INVENTION

The malting process consists of five identifiable phases, which aredrying, steeping, germinating, kilning and roasting.

The earliest historical records of the malting process go back toancient Egypt. Through the ages this process has progressively becomemore mechanised at each phase, with a multiplicity of different methodsemployed, including the Saladin and Wanderhaufen germinating systems inthe early 1960's. These systems produce good quality malt using “Bottomto Top Turners” working in long rectangular “streets” or boxes, duringthe germinating phase. These “turners” are machines which turn over ormix the mass of grain and are moved from box to box or end to end, asthe process requires. The turners pick up the raw material at the bottomof the raw material mass (“piece”) and drop it at the top, to fullyaerate the piece and increase the volume during the germination phase.This is achieved by driving scoops or enclosed Archimedean screws intothe bottom of the germinating piece and depositing the turned, and nowlightened (increased in bulk volume), piece behind the advancing turningmachine. None of the systems employed in merchanised malting processesachieve the preferred option of bottom to top turning during the otherfour phases of the malting process as well as during the germinationphase.

It has been said that “Turners (during germination) must “lighten thepiece,” separate matted rootlets and allow the air to pass freely. Goodturners can increase the volume of the piece by one quarter to onethird.” (Malting and Brewing Science, Briggs, Hough, Stevens and Young).

The drive to improve efficiency, at the lowest unit cost, has reducedthe first four phases of the malting process (drying, steeping,germinating and kilning) to large batches produced in one or twocircular vessels which use a multiplicity of prime movers within thevessel. (The last phase, roasting, is normally conducted separately fromthe first four phases). This condensing of the process has compromisedmalt quality with particular regard to loss of the benefit of turningthe raw material from bottom to top. If the grain is not treatedhomogeneously in the processing equipment then a homogeneous productdoes not ensue. These large circular vessels operate by either movingthe raw material towards a row of fixed stirring machines or driving arow of stirring machines through the static raw material. The stirringmachines employed are open helical screws, which prevent the rootletsfrom matting during the germination phase, but do not turn the rawmaterial from the bottom to the top during any of the first four phasesof the malting process. In particular they do not enhance aeration, orincrease the volume of the piece by one quarter to one third during thegermination phase. A further defect, entailing further cost, associatedwith this type of equipment is that additional drives are also requiredto load, strip and discharge the vessels.

An object of the present invention is to provide improvements relatingto the equipment used in the malting process, wherein the aforesaiddisadvantages of the current processing equipment are obviated ormitigated.

A further object of the invention is to provide a single multi-purposevessel equipped to carry out any or all of the five stages of themalting process, namely drying, steeping, germinating, kilning, androasting. A yet further object of the invention is to provide equipmentthat permits the operation of the preferred practice of turning thematerial from the bottom of the grain mass to the top of the grain massat any or all of the five stages of the malting process. A still furtherobject of the invention is to provide improvements to the quality ofmalt, especially with regard to homogeneity of the grains, by carryingout the malting process utilising the equipment of the presentinvention.

SUMMARY OF THE INVENTION

Accordingly the aforesaid objects are addressed in that the presentinvention provides a single multi-purpose vessel, wherein all fivestages of the malting process can be conducted to good effect whilstavoiding the compromised quality of the product such as is produced bythe currently available equipment which uses large vessels with amultiplicity of prime movers to carry out the various operationsrequired.

According to one aspect of the present invention, a beneficial featureof the invention is the provision of a centrally located drive mechanism(or drive mechanisms) to be described hereinafter by reference to theaccompanying drawings. Such a drive as proposed herein powers theloading and levelling mechanism, the “turning arm and stripping plates”and the mechanism for lifting the grain collected by the strippingmechanism from the bottom of the piece to the top for redistribution bythe loading and levelling arms. Thus according to that aspect of theinvention there is provided a drive mechanism comprising, drive means, adriven shaft arranged to be upstanding in use in relation to the piece,a plurality of radially positioned upstanding plates arranged in adeclining stages of height and mounted for rotation substantially in theplane of the piece about said shaft, and preferably each of said platesis positioned by a radial off-set with respect to its radially inwardneighbour such as to lag by a certain angular amount such that theoverall effect is to provide a series of stripping plates constituting asweeping arm extending from the shaft and having a curvature whereby thedistal end of the arm with respect to the mounted end of the arm trailsduring each rotation of the shaft.

The function of the sweeping arm is to carry the stripping platesrepeatedly through the grain mass in such a way that a thin layer ofgrain, substantially that which is adjacent to the bottom of the vessel(typically a foraminated floor), is collected by the stripping platesand propelled by the forces of their motion towards a centrally placedhopper set in the floor of the vessel .

According to a further aspect of the invention, there is provided a masstransfer device for lifting grain mass collected in the aforesaidhopper, to an elevated discharge level, and juxtaposed with respect tosaid device, for the purpose in use of collecting discharged grain massfor loading back into the piece, there are provided a plurality ofloading arms mounted upon a driven shaft for rotation substantially in aplane parallel with the piece. In a preferred embodiment each loadingarm having a curvature whereby the distal end of the arm with respect tothe mounted end of the arm trails during each rotation of the shaft, thesaid curvature preferably corresponding to the curvature of theaforementioned stripping plate arms. The mass transfer device ispreferably an Archimedean screw conveyor device.

According to a preferred aspect of the invention, the stripping platearms and loading arms are mounted upon a common drive shaft and spacedapart thereon by a distance corresponding in use to maximum height ofthe piece, in order to prevent the loading arms dragging through thepiece during processing. In a most preferred aspect of the invention theloading arms are moveable in distance from the stripping plate arms sothat they can be adjusted to correspond closely to the top of the pieceat each stage of the process, to facilitate even distribution of thegrain.

According to yet an other aspect of the invention there is provided aprocess vessel incorporating a generally upstanding cylindrical walledsection having a drive means located in an upper part thereof, andoperationally connected to an upright centrally positioned drive shaftprovided at an upper end thereof a plurality of curved loading arms, andat a lower end thereof a plurality of correspondingly curved strippingarms formed from a series of upstanding plates arranged in a decliningstages of height, the said vessel having a floor for receiving in use apiece, and a centrally positioned piece mass collection hopper, the saidshaft being positioned above said hopper and containing within itslength a mass transfer device to elevate grain mass from the hopper toan upper discharge port of the shaft adjacent to the loading arms. Thevessel is suitably equipped as necessary with aeration and heating meansas is understood in the art to be required for a malting process.

From the hopper in the vessel floor, the grain is lifted by a masstransfer means or mechanism, preferably a screw conveyor located in asleeve (said sleeve serving as the shaft surface), towards the top ofthe vessel where it can be redistributed onto the grain mass with theassistance of the loading arms. Thus bottom to top turning of the graincan be achieved by the combined action of the lower turning arms withheight-staged stripping plates together with the centrally locatedlifting mechanism and upper loading arms.

The stripping plates can be carried on any number of turning arms,dependent on the desired size of the malting vessel or batch quantity. Apreferred embodiment consisting of two opposing arms is shown in theExample and the accompanying drawings. The stripping plates are piecesof metal or other suitable material that are fixed to the turning arm orarms in a generally upright manner and are sized and shaped in such afashion that they act as deflectors or ploughs when the arm is rotated,directing a thin layer of the grain towards the centre of the bottom ofthe vessel by the repeated passage of the plates through the grain mass.

The outermost stripping plate directs or deflects a portion of grainfrom the outermost part of the bottom of the vessel into the path of thenext innermost plate. When the next arm carrying stripping platespasses, the grain originally from, the outside portion of the bottom ofthe vessel is again moved one further unit (the radial distance swept bya stripping plate) towards the centre of the vessel. At the same time,because the plates increase in height towards the centre of the vessel,a portion of the grain that has dropped into place from the grain abovethe stripping plates following the previous passage of stripping platesis also moved inwards. By this method, successive passages of theturning arm or arms move a thin layer of the grain from the entire baseof the vessel into the central hopper. By repetition the entire batch ofgrain is taken from the base of the vessel and transported to the top ofthe grain mass via the lifting mechanism. This procedure can becontinued to turn over, loosen, aerate, or assist heating or cooling thegrain mass, as often as desired at any stage of the malting process.

When employed in lifting the grain from the bottom of the vessel duringturning procedures the lifting device can also serve to aerate orincrease the bulk volume of the grain mass. When an Archimedean screwoperating in a sleeve is employed as shown in the Example, the rate ofvolume lift of the screw is set to exceed the rate at which thestripping plates deliver material to its feed hopper. This enhances theaeration and avoids damaging the grain during transport. The liftingdevice is also usefully employed at the end of the process or a chosenprocess stage to discharge the grain via a discharge chute.

The loading arms are employed in distributing the grain both when thevessel is being loaded and also when the batch is being turned. In apreferred embodiment they are located directly above the trailing edgeof the turning arms and follow the same curve or profile. It is alsopreferred that they can be raised or lowered to match the batch volumein the vessel so that they can be set to distribute and even out thematerial effectively.

The vessel of the invention is also equipped with a number of otherfeatures to enable all aspects of the malting process to be carried out.These include insulation, air and water inlets and outlets, heatexchangers and means of humidifying the air. This allows appropriatelyconditioned air to be fed into the vessel depending on the stage of themalting process that is being carried out. For instance, roasting of themalt, if it is required, is conveniently carried out in the vessel,immediately following the germinating phase, by supplying hot airthrough the foraminated floor of the vessel whilst turning the piece.

Thus it will be understood that according to this invention there isprovided a method of turning a piece that comprises introducing a massof grain to a vessel to form a piece, arranging therein an upstandingdriven shaft about which there are arranged curved turning armscomprising height-staged plates of radially declining height, at a lowerend of the shaft, and collector loading arms of corresponding curvatureat an upper end of the shaft, said shaft incorporating within its lengtha mass transfer device, and having a collection hopper at the lower endfor introducing grain mass to the transfer device, and discharge portsat its upper end for discharging elevated grain mass, operating thedriven shaft to turn the respective upper and lower arms, whereby grainmass at the lower end of the shaft migrates radially inwards to thecollection hopper, elevating the grain mass to the discharge ports,collecting the grain mass and distributing same over the piece, saidsteps being operable in a continuous cycle for a period of time adequatefor the purpose of a malting process.

The aforesaid mechanisms, vessel and method are ideally used to conductthe whole malting process within a single vessel, the manner of such usebeing more fully described hereinafter by way of illustrative examplewith reference to the accompanying drawings in which:

FIG. 1 shows a cross section of the vessel equipped for carrying out allthe stages of the malting process; and

FIG. 2 shows a plan view of an embodiment of the turning arms andheight-staged stripping plates of the invention.

A vessel adapted for the performance of a malting process is representedby the cross sectional view of the vessel as shown in FIG. 1. The mainvessel 1 is built out of stainless steel. At the base of the vesselthere is an air inlet duct 2. This duct is fixed to the side of thevessel with a fall to drain 3 to aid drainage of the steep liquor. Thisalso enables self-cleaning of debris and culms disposal after drying,kilning and roasting. The air inlet duct serves to introduce air to thevessel via a plenum chamber 6 and thence the perforated floor. The airis warmed and or humidified as required by the stage of the processusing proprietary equipment. A similar air outlet duct 4 is also fixedto the top of the vessel. (The air inlet and outlet ducts house thefollowing proprietary equipment, which is not shown:- Air heatexchanger, multi-louver dampers, butterfly valve, spray chamber and acentrifugal multi-speed fan).

The vessel houses a mass transfer mechanism including arms 12, 25 thatsweep around the vessel at upper and lower levels, said arms beingmounted on a centrally positioned drive shaft 17 that also incorporatesa mass elevation device such as a screw conveyor 10. This mechanism isput to the following purpose.

During the germination stage of the malting process high concentrationsof carbon dioxide suppress respiration and cause “hot spots” in thepiece 5. Turning the piece from bottom to top, and lightening it to aidaeration, addresses this problem and improves evenness of modificationduring both steeping and germination. The airflow arrangements in thevessel permit periodic reversal of flow through the piece to remove thecarbon dioxide gradient during germination. These procedures will alsoenhance the evenness of drying and colour formation during thesubsequent stages of kilning and roasting. This significantly improvesthe finished malt quality and homogeneity.

The plenum chamber 6 has a fall to the inlet duct to assist drainage anddebris removal. There is a circular manifold 7 for high-pressure waterinjection during vessel cleaning and can also be used for air injectionto rouse the piece and aerate during steeping. It can further be usedfor dousing during roasting. The static, stainless steel, foraminatedfloor 8 has a foraminated conical feed hopper 9. The raw material is fedvia this hopper to the mass elevation device in the form here of anArchimedean screw 10, during turning, or to the discharge point 11 atthe end of each or any of the five process stages that can be carriedout in the vessel. The rate of volume lift of the screw conveyor ischosen to exceed the rate of vessel stripping (removal of grain from thevessel) to enhance aeration of the piece being turned duringgermination, and to avoid damaging the raw material or over loading theturning arm 12. The central section 13 of the perforated floor is partof the turning arm, which rotates above the conical hopper. This centralsection has two curved stripping slots 14 (See FIG. 2). These slotsreceive the grain collected by the action of the stripping plates anddeliver it into the hopper 9. The slots are protected by suitableskirting (not shown) from grain in the body of the vessel falling inunder gravity. This means that substantially only grain that has beencollected by action of turning arm and stripping plates is fed to thescrew conveyor.

The exterior of the vessel is coated with insulation 15. This isvaluable for all five phases of the process where appropriatetemperature control is needed to attain a quality product.

The central drive 16 is located at the top of the vessel and providesthe motive force for the turning and loading arms and the Archimedeanscrew. Both the Archimedean lifting screw and the outer sleeve 17 rotateon the same centre of rotation. The outer sleeve acts as the drive shaftfor both the turning and loading arms. The turning arms also carry thestripping plates 18, which move the raw material towards the centre ofthe vessel as discussed above in the Summary of the Invention. Thestripping plates in this embodiment are rectangular plates fixedvertically to the turning arms, angled to direct the grain acrosstowards the centre of the vessel floor. The height of the strippingplates increases towards the centre of the vessel to provide therequired action as discussed previously. The height of the strippingplates nearest the centre of the vessel corresponds to the height usedfor the stripping slot 14 with an incremental decrease from plate toplate towards the circumference of the vessel.

The power required to turn the arm is a function of the need for it tobe turned. For example during the germination phase a well turned andlightened piece will permit easier movement of the turning arm than adense compacted mass. This relationship can be applied to automaticallyincrease or decrease the rate of rotation of the turning arms during anyphase of the process by the appropriate use of an automatic systemcontroller e.g. including a microprocessor. The airflow and airtemperature controls can also be similarly moderated by the state of thegrain mass as may be detected by the force required to move the turningarm. Thus increased resistance to turning of the arms indicates acompact state in the piece, thus requiring further work to lighten thepiece which will be detectable when resistance eases.

The Archimedean sleeve is located in top 19 and bottom 20 bearings. Thebottom bearing is secured by means of horizontal supports from thecircumference 21 and the base 22 of the vessel. These supports also actas supports for the perforated floor. A load bearing safetyplate/distance piece 23 is fixed circumferentially to prevent thestripping plates from coming into contact with the perforated floor. TheArchimedean sleeve has two slots cut into the top section 24. These actas discharge points for the raw material being lifted from the bottom ofthe vessel to the top. A distribution chute allows the raw material todrop in front of the loading arms 25, which then spreads it evenly overthe top of the piece. These loading arms are located directly above thetrailing edge of the turning arms and follow the same curve profile.This arrangement maintains an even raw material depth to avoid airchannelling. These loading arms are attached to support brackets 26 viaracks and pinions 27. These raise and lower the loading arms as neededto permit proper control of the distribution of the grain batch. Thelevel of the batch fluctuates due to the change in moisture content andbulk density of the raw material during the five different phases of theprocess. Further the high quality bottom to top turning that theequipment permits leads to substantial volume increases duringlightening procedures carried out during any one of the process stages,especially during the germination phase.

The drive for these racks and pinions is transmitted via. drive shafts,which have splined couplings 28 to allow for the rise and fall of theloading arms. The drive end of these drive shafts mesh into a doublesided cog 29 which is mounted in a free running bearing 30 at the top ofthe vessel. The double-sided cog is rotated externally when the loadingarms are required to be raised or lowered through the drive shaft 31this can be achieved either manually or via the indexing motor 32.Sensors located at the loading arm tips 33 supply the signal for thismotor to either raise or lower the loading arms. In the absence of asignal to the indexing motor the drive shafts and double-sided cogfree-wheel, so maintaining the set height of the loading arms.

Raw material is supplied via the inlet pipe 34 at the beginning of eachbatch to be processed.

All five phases of the malting process can be carried out in one vesselas described in this example. However, depending on the scale of maltingoperation required a multiplicity of vessels can be utilised forefficiency of throughput. Whilst it is conceivable to house a pluralityof mutually laterally spaced lifting and turning mechanisms in a singlehousing to process a piece of substantially large surface area, thisarrangement may be liable to leave “dead spots” in the piece whereelevation and turning is ineffective or inefficient. Therefore, theconfinement by use of a cylindrical wall section around the lifting andturning mechanism is considered to be the best mode of operation.

Normally the drying phase is kept separate from the following fourphases with the exception of some specialist roasted products. Steeping,germination and kilning phases can all be run consecutively within onevessel or by transfer to other vessels to maximise process flexibilityand energy conservation. If a multiplicity of vessels is used two ormore phases can be operated concurrently if desired to maximisethroughput With the exception of roasting raw material after the dryingphase for specialist products, as mentioned above, the roasting phasenormally commences after the germination phase and replaces the kilningphase by simpler applying much higher air on temperatures to the maltedmaterial.

1. A method for carrying out a malting process wherein a mass of grainis introduced into a vessel, the portion of the grain that issubstantially adjacent to the base of the vessel is moved, in anincremental fashion, to a collection hopper in the centre of the base ofthe vessel by the action of height-staged plates of radially decliningheight mounted on turning arms, said turning arms rotating in asubstantially horizontal plane and being located at the lower end of anupstanding driven shaft, the grain collecting in said collection hopperis then elevated to the top of the mass of grain by a mass transferdevice and distributed over said mass of grain by the action of loadingarms located at the upper end of the upstanding driven shaft such thatthe overall effect is to turn over the grain mass introduced to thevessel in a bottom to top fashion, said turning over being operable in acontinuous cycle for a period of time adequate for the purpose of amalting process.
 2. A method for carrying out a malting processaccording to claim 1 wherein the process is a drying process and thevessel is supplied with conditioned air.
 3. A method for carrying out amalting process according to claim 1 wherein the process is a steepingprocess and the vessel is supplied with means for the supply and removalof water and conditioned air.
 4. A method for carrying out a maltingprocess according to claim 1 wherein the process is a germinatingprocess and the vessel is supplied with conditioned air and water.
 5. Amethod for carrying out a malting process according to claim 1 whereinthe process is a kilning process and the vessel is supplied withconditioned air.
 6. A method for carrying out a malting processaccording to claim 1 wherein the process is a roasting process and thevessel is supplied with conditioned air and water.
 7. A method forcarrying out a malting process according to claim 1 wherein the processconsists of any combination of drying, steeping, germinating, kilningand roasting.
 8. An apparatus for carrying out malting processescomprising a vessel provided with a drive means, a driven shaft arrangedto be upstanding in use in relation to the grain mass, a plurality ofturning arms mounted for rotation substantially in the plane of thepiece about said shaft, said turning arms comprising a plurality ofradially positioned upstanding plates arranged in declining stages ofheight, such that the overall effect is to provide a series of strippingplates for moving grain incrementally from the base of the vessel, acollection hopper located at the centre of the base of the vessel, and amass transfer device for lifting the grain mass from the collectionhopper to an elevated discharge level, a plurality of loading armsrotating substantially in the plane of the piece mounted upon a drivenshaft, for redistributing the elevated grain onto the grain mass.
 9. Anapparatus for carrying out a malting process according to claim 8wherein the plurality of radially positioned upstanding plates are eachoffset radially by a certain angular amount, constituting a sweeping armextending from the shaft and having a curvature whereby the distal endof the arm with respect to the mounted end of the arm trails during eachrotation of the shaft.
 10. An apparatus for carrying out a maltingprocess according to claim 8 wherein the mass transfer device is locatedwithin the driven shaft which drives the loading arms and the strippingplates.
 11. An apparatus for carrying out a malting process according toclaim 10 wherein the mass transfer device is a screw conveyor located ina sleeve.
 12. An apparatus for carrying out a malting process accordingto claim 8 wherein the said loading arms rotate substantially in a planeparallel to the grain mass.
 13. An apparatus for carrying out a maltingprocess according to claim 8 wherein the said loading arms have acurvature whereby the distal end of the arm with respect to the mountedend of the arm trails during each rotation of the shaft, the saidcurvature corresponding to the curvature of the aforementioned sweepingarm.
 14. An apparatus for carrying out a malting process according toclaim 8 wherein the loading arms are moveable in distance from thesweeping arm.
 15. An apparatus for carrying out a malting processaccording to claim 1 wherein the vessel is substantially cylindrical insection and is further equipped with a foraminated floor, insulation,air and water inlets and outlets, heat exchangers and means ofhumidifying the air.
 16. (canceled)